Lipid vesicles are formed so that they contain pure water. If these vesicles are transferred to a solution that contains a rather high concentration of solutes, what will be the net direction of water movement?

a) It will not move at all.

b) It depends on what solute is dissolved in the exterior solution.

c) It will move out of the vesicles.

d) It will move into the vesicles.

c) It will move out of the vesicles.

A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume?

a) Solution A: 1.4% (m/v) starchb) Solution B: 7.62% (m/v) starch

a) Solution A: 1.4% (m/v) starch (The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.)

A semipermeable membrane is placed between the following solutions. Which solution will increase in volume?

a) Solution C: 9% (m/v) NaClb) Solution D: 12.4% (m/v) NaCl

b) Solution D: 12.4% (m/v) NaCl (The water molecules actually move in both directions, but they move to a greater extent toward Solution D because it has a higher solute concentration than Solution C. This net movement of water molecules causes Solution D to increase in volume and Solution C to decrease in volume.)

What distinguishes facilitated diffusion from simple diffusion?

a) Molecules move from a region of lower concentration to a region of higher concentration.

b) No energy is used to move molecules across the membrane.

c) Membrane proteins help move molecules across the membrane.

d) Molecules move from a region of higher concentration to a region of lower concentration.

c) Membrane proteins help move molecules across the membrane.

Which of the following transporters does not use passive transport to move molecules across a membrane?

True or false? Active transport differs from passive transport in that active transport does not require an input of energy.

False

Which membrane protein would be used to move glucose across a membrane from a region of higher concentration to a region of lower concentration?

a) Transporterb) No protein is necessary.c) Pumpd) Ion channel

a) Transporter

(The GLUT-1 transporter assists the diffusion of glucose through the membrane.)

Which of the following statements is true about the net movement of an ion across a membrane by passive diffusion through a membrane channel?

a) The charge on the other side of the membrane is generally the opposite of the ion's charge.

b) There is a higher concentration of ions on the side of the membrane toward which the ion diffuses.

c) For every ion that diffuses through the membrane, a different ion diffuses in the opposite direction.

d) The cell expends energy as the ion passes through the membrane.

a) The charge on the other side of the membrane is generally the opposite of the ion's charge.

(Ions tend to move toward regions of unlike charge.)

True or false? During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell.

False(The sodium-potassium pump maintains a state in which the concentration of sodium is low inside the cell relative to the outside and the concentration of potassium is high inside the cell relative to the outside; thus, three sodium ions are pumped out of the cell and two potassium ions are pumped into the cell against the electrochemical gradient.)

Lactose transport by membrane proteins occurs under conditions in which the concentration of lactose inside the cell is higher than the concentration outside the cell. What type of transport is used to move lactose into the cell?

(Under these conditions, lactose moves against its concentration gradient, so its transport will require energy.)

In cells, membrane proteins are responsible for the passage of substances that can't cross the membrane on their own. Channels and transporters are involved in facilitated diffusion. Pumps are involved in active transport. In terms of their properties or functions, which statement most accurately describes how these three types of membrane proteins compare?

a) Among the three types, only pumps are thought to undergo a shape change as part of their function.